Circuit Description
The IC module determines crankshaft and camshaft position and fires the appropriate spark plug. The IC module also creates 4X and 24X reference pulses that are supplied to the PCM. The PCM uses these reference circuits to determine fuel delivery and spark timing. Most failures in the Ignition Control system will set a PCM DTC. Always perform the Powertrain On Board Diagnostic (OBD) System Check and, if necessary, the Engine Cranks but Does Not Run diagnostic table BEFORE performing any Ignition System diagnosis.
Test Description
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The Engine Cranks but Does Not Run table must be performed BEFORE using this diagnostic procedure.
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Observe the Engine Speed parameter on the scan tool while increasing spark RETARD by 10 degrees. The PCM will attempt to keep the engine speed at the Desired Idle during spark retard by slightly increasing spark advance. The engine speed may initially drop by 50 RPM then increase slightly to average 30 RPM less than the RPM observed during normal spark control.
If engine speed fails to decrease proceed to Step 4 of DTC P1350 Ignition Control System diagnosis.
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Observe the scan tool status for the extended travel brake switch. Ensure that the extended travel brake switch status is not applied all the time. When the extended travel brake switch is applied the PCM will operates at high throttle angles causing timing and fuel reduction during acceleration.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||
2 | Using a scan tool check for stored History PCM DTC's. Are any DTC's set? | -- | Go to DTC'sthat are set | |||||||||
Attempt to start and idle the engine. Does the engine start? | -- | |||||||||||
Does engine speed decrease as spark is retarded? | -- | Go to DTC P1350 Ignition Control System (Step 4) | ||||||||||
Is a Miss, Stumble, or Hesitation observed? | -- | |||||||||||
6 | Were any other driveability symptoms observed? | -- | Go to Symptoms | System OK | ||||||||
7 |
Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 8 | ||||||||
8 | Connect the test lamp between terminal C and a good engine ground. Does the test lamp illuminate? | -- | ||||||||||
9 | Repair the open ground circuit to the IC module. Is the repair complete? | -- | -- | |||||||||
10 | Repair the cause of no voltage to the IC module. Possibilities include the following:
Is the repair complete? | -- | -- | |||||||||
11 |
Was terminal contact repaired? | -- | ||||||||||
12 | Replace the IC module. Refer to Ignition Control Module Replacement . Is the replacement complete? | -- | -- |
